A common method of moving parts or components along a manufacturing assembly line is by means of overhead conveyors. Such conveyors may be formed of a number of wheeled trolleys that ride along a guideway or track in a continuous closed loop. The trolleys are connected by a conveyor chain formed of a number of connected links, and the parts or components are suspended from the trolley.
The conveyor chain is typically driven by a motorized sprocket assembly that provides force for powering the wheeled trolleys along the guideway or track. Although the wheeled trolleys and the parts or components suspended from the trolley have their weight supported by the guideway or track, the conveyor chain is still subjected to wear over an extended period of time. These conveyor chains may be very lengthy, as they may travel and extend throughout a large production facility. Thus, such conveyor chains may be subjected to numerous random forces and stress as well as a variety of environmental conditions such as heat fluctuations, oils, solvents, and other caustic solutions.
In order to reduce the wear on the wheeled trolleys and the conveyor chain, lubrication oil is typically applied to the wheeled trolleys along the guideway or track and to pivot pins that connect successive links of the conveyor chain. The lubrication oil reduces friction and heat created by the stresses that are generated through the forces applied to the wheeled trolleys and the conveyor chain. Automated lubrication oil systems have been created to automatically apply the lubrication oil to the wheeled trolleys and the conveyor chain wherein spray nozzles or other applicators are mounted adjacent the wheeled trolleys and the conveyor chain to apply the lubrication oil. On occasion, such spray nozzles or applicators may become dislodged from their proper position due to vibration from the wheeled trolley and the conveyor chain or from random forces that may occur in a manufacturing environment. When this occurs, the lubrication oil may not be properly applied to the wheeled trolley and conveyor chain, and thus, the wheeled trolley and conveyor chain may wear at a faster rate than usual. There are no known monitoring systems for ensuring that such lubrication is being properly applied to the wheeled trolleys and conveyor chain, and therefore, it would be beneficial to provide a monitoring system to ensure for the proper lubrication by such automated lubrication systems.
Although properly lubricating the conveyor chain will assist in reducing wear, wear of the conveyor will inevitably occur due to the above-noted conditions. The wear of the conveyor chain should be monitored in order to prevent the conveyor chain from breaking or possibly damaging other components of the conveyor system. One of the most closely watched chain wear parameters is chain stretch that is defined as the linear distance in which the chain lengthens over a period of time due to wear. Chain stretch often occurs through the eventual wearing of the conveyor chain's pivot pins which, as previously noted, are utilized to connect successive links of the conveyor chain. The movement of the pivot pins within the apertures of the links eventually wears the pivot pins and creates “slop”. This “slop”, along with yielding of the links, will essentially make the conveyor chain longer when pulled taught.
Minor wear or chain stretch is allowable and expected within the industry, but when chain stretch becomes excessive, it may cause numerous problems. For one, the sprocket may not be able to properly engage the conveyor chain should the chain stretch become excessive enough that the teeth of the sprocket skip a space between links or apply forces to a link that may bend or damage the conveyor chain. Also, extensive chain stretch may cause the conveyor chain to sag, thus affecting the smooth travel of the wheeled trolleys along the guideway or track. Yet, the greatest concern is that excessive chain stretch may lead to the eventual thinning and breaking of the conveyor chain.
In order to monitor the chain stretch of a conveyor chain, a certain length of the conveyor chain is often measured manually to ensure that the chain stretch does not exceed a predetermined value. It is well known and common in the art to monitor and measure ten foot sections of the conveyor chain. The problem with making such manual measurements is that the conveyor chain must be stopped in order to make a proper measurement. This requires the entire conveyor to be shut down, which prevents and delays the parts or components delivered by the conveyor from being supplied to the assembly or production line. Obviously, this creates inefficiencies that are undesirable in a production environment.
In addition, manual measurements of chain stretch typically have the problem of being inaccurate, as they are conducted with tape measures, which can hardly be considered accurate for repetitive measurements of ten foot chain lengths. Also, the ten foot sections of conveyor chain selected for measurement is typically random, and therefore, no recorded history exists or is maintained as to the wear of that particular section of conveyor chain. This becomes an even greater disadvantage when a portion of the chain has been replaced by either a different manufacturer or different material, and thus, an evaluation as to the performance and wear of the individual sections of the conveyor chain cannot be made. Furthermore, manual chain wear measurements rely on an operator to continually measure the conveyor chain. Should the operator fail to continually monitor the chain, any number of the above-noted results can occur.
More recent designs have utilized sensors spaced along the conveyor chain at predetermined distances to generate signals corresponding to the presence and absence of chain links within the conveyor chain. The signals are processed and compared to predetermined values to determine if any of the chain links have excessive wear or stretching. Although the process can occur without stopping the conveyor chain, the inspection and maintenance of the conveyor chain still requires the conveyor chain be stopped and manually inspected. Since most industrial conveyor chains extend through manufacturing facilities and are relatively long, the actual discovery and maintenance of a worn chain link of the conveyor chain can require an excessive amount of time which is undesirable in an industrial environment. Thus, it would be desirable to provide a conveyor chain monitoring system that accurately and immediately identified the location and nature of the wear of the conveyor chain so as to reduce the time associated with stopping, identifying, and maintaining the conveyor chain.